Although we need to remember that this is a work of fiction, the use of Nikola Tesla as one of the Five is perhaps the biggest stretch of all. But … it is by no means implausible. In 1886, the year the Five injected themselves with the vampire blood, the "real" Tesla had broken off with Edison, lost control of his own company (Tesla Electric Light & Manufacturing) and was supposedly working in New York as a laborer in order to raise funds for his next project. Given laborers wages then, and now, is it really practical that Tesla could raise sufficient funds working as a day laborer? Perhaps a trip to London to raise venture capital is not so farfetched? In any case, the "real" Tesla resurfaced in 1888 - demonstrating his brushless AC induction motor to the American Institute of Electrical Engineers, after which he began his work with George Westinghouse.
Besides working on an ion-propelled "flying saucer" - and a host of other futuristic technologies - Tesla, who had demonstrated wireless energy transmission almost fifty years earlier, did indeed work on what he described as a "superweapon that would put an end to all war" (1937) - what today we would call a "directed-energy" or "particle beam" weapon (which the press of the time labeled as a "peace ray" or "death beam"). Apparently, before Einstein alerted FDR to the incredibly destructive scientific power being unleashed by the Nazi's (1940), neither the U.S. nor the European powers he offered his technology to were interested enough to fund the manufacture of his device.
Supposedly, the "real" Nikola Tesla died poor and alone, of heart failure, on January 7, 1943. Only after his death did the United States Supreme Court uphold his patent on the technology that formed the basis for radio communications in the United States. At the time of his death, Tesla was still working on the "Teleforce" weapon, or "death ray", that he couldn't get the U.S. War Department interested in. However, shortly after he died, Tesla's papers, prototypes, project notes and lab properties were impounded by the United States' Alien Property Custodian office - despite the fact that he was a legally naturalized U.S. citizen. After being contacted by the War Department, J. Edgar Hoover and the FBI seized - and, along with other federal officials, microfilmed - his papers and personal effects, before declaring them potentially dangerous and "Top Secret".